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Quantum Information and Measurement (QIM)

Sensitivity enhancement by mode entanglement in distributed phase sensing

Xueshi Guo, Johannes Borregaard, Casper R. Breum, Shuro Izumi, Mikkel V. Larsen, Jonas Schou Neergaard-Nielsen, Ulrik L. Andersen

Published Jan 1, 2019• 2 citations
Publisher

Abstract

We investigate the sensitivity of distributed phase sensing with squeezed state probes. By creating mode entanglement between probes with a beam-splitter network, sensitivity enhancement over independent probes is observed experimentally for the first time.
DOI
10.1364/qim.2019.s4a.4

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Distributed quantum sensing is an emerging application of quantum networking, where entangled probe states are employed to sense combinations of delocalized parameters with enhanced precision relative to using separable states. Squeezed states of light are a prime resource for experimental demonstrations of entanglement-enhanced sensing, because they can be generated and entangled deterministically. Existing distributed quantum sensing experiments have been fundamentally limited in scalability due to their bulk-optic architectures. Meanwhile, integrated photonics provides a scalable and compact platform for quantum sensors. Here we demonstrate entanglement-enhanced sensing of linear functions of four phase shifts in an integrated photonic circuit. We find an entanglement-enhanced precision of 0.199(16) dB below the shot noise limit compared to 0.041(18) dB for separable states. A four-mode entangled state is generated on-chip with entanglement verification and phase sensing also performed on-chip with an array of four integrated homodyne detectors.
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